> >> >
> >> > void foo(int *p) {
> >> > if (!p) { printf("null pointer\n"); }
> >> > volatile bool b = false;
> >> > if (b) { abort(); }
> >> > *p = 0;
> >> > }
[...]
Why not simply name this attribute `[[do_not_optimize]]`?
Google Benchmark already has this, and I wouldn't be surprised if more than one corporate codebase also has it. It's a pure library feature, implementable in plain old standard C++.
// In another .cpp file:
void escape(void*) {}
// In the header file:
extern void escape(void*);
template<class T> void DoNotOptimize(T&& t) { escape(&t); }
void foo(int *p) {
if (!p) { printf("null pointer\n"); }
DoNotOptimize(p);
*p = 0;
}
The compiler can see that `escape(&p)` is called, but it doesn't know at compile time whether `escape` might throw or terminate, so it can't assume that the line `*p = 0` will necessarily be reached (so it can't hoist that line upward and it can't remove the null-check).
–Arthur